Kohlberg Kravis Roberts & Co. co-founders Henry Kravis and George Roberts may have missed out on tens of billions of dollars by deciding to roll the dice now on its Johnny-come-lately initial public offering.

Yesterday, KKR’s much-anticipated IPO – slated for the fourth quarter – was met with a huge thud on Wall Street as the broader financial markets and mounting worries about oil prices helped sink the Dow Jones industrial average by nearly 240 points.

KKR’s planned offering puzzled many on Wall Street, especially given it comes as leveraged buyout shops and financial firms that helped finance big LBOs have been bashed by the ongoing credit crisis.

Indeed, the unusual timing for the deal led one analyst to ask during KKR’s call to announce the deal yesterday, “Why now?”

For KKR, the complicated IPO, which would value the buyout shop at as much as $19 billion, allows the firm to kill two birds with one stone by raising capital at the same time it extends a life buoy to its ailing European affiliate KKR Private Equity Investors, or KPE.

Plans for KKR are to essentially acquire KPE at a discount, delist it from the Euronext stock exchange in Amsterdam and relist it on the New York Stock Exchange as KKR.

Originally, KKR hoped its IPO would place the value of its operation at about $26 billion but a rapid deterioration in the credit markets and the mortgage contagion that has whacked financials forced the firm to table its plans for more than a year.

Now it faces a big discount on its offering.

Kravis’ IPO plans in many ways was a push to keep up with the Joneses – or more accurately, the Schwarzmans – and stay competitive, especially after rival Blackstone Group raised $4.1 billion with an IPO priced at $31 a share.

Blackstone’s offering made co-founder Stephen Schwarzman even more of a billionaire.

However, Wall Street’s love affair with private-equity offerings has waned significantly, with Blackstone losing nearly half its value since it went public.

Long-term, KKR hopes that despite the unfavorable environment that it can use the proceeds from the offering to attract and keep talent.

“We believe there is a significant opportunity to leverage out intellectual capital and long-standing relationships with our investor base to drive this business over several quarters,” Kravis said during the call.